Hems are formed in banners in order to strengthen the material making up the banner. Additional strength is desirable when inserting grommets into banners for purposes of fastening the banner to a wall, balcony, window or other structure. A hem is formed along an edge of the banner and one or more grommets are applied thereon. A stronger connection is formed by having the grommet disposed through a hem of the banner as opposed to being disposed through a single layer of the material making up the banner.
Lettering or graphics may be applied to the banner either through hand painting or by using a computer to plot letters with adhesive backing (vinyl graphics) and then subsequently applying the letters to a banner that already has hems and grommets. Digital ink jet printers have recently been used to enable banner printers to print directly onto the banner. However, digital ink jet printers are not capable of accommodating a banner that has hems and grommets. It is therefore the case that digital ink jet printers print onto a banner that is then subsequently finished by having hems and grommets applied thereon. Sign shops and print shops will either apply hems and grommets in house or will send the printed banners to an outside vendor for application of these features.
Hems can be applied to printed banners in a number of manners. Sewing is one technique that can be used to form hems. However, sewing requires a skilled operator in addition to a sewing machine. Aside from general maintenance such as the calibration of timing, sewing machines commonly break down due to incidents such as broken needles and broken threads. Further, sewing a hem into a banner causes stitches to be present on the printed side of the banner. The stitches may be problematic in that they reduce the amount of area available for printing and can interfere with the printed image.
Another method used to form hems into banners involves the use of double sided tape. Here, the double sided tape is applied along the inside length of a banner proximate one of its edges. The paper or plastic strip on the exposed side of the tape is removed, and the edge of the banner is folded downward over the tape in order to affix it thereon. Formation of a hem with tape may be advantageous over sewing because it eliminates the presence of stitches on the printed side of the banner. Also, the formation of a hem with double sided tape generally requires less skill than forming a hem through sewing and consequently eliminates the need of maintenance, repair and downtime associated with the use of a sewing machine. Hemming with double sided tape is also advantageous over other methods of hem formation such as heat-sealing and sonic welding in that forming a hem with tape is considerably less expensive.
Although advantageous in certain aspects, forming hems with double sided tape poses various challenges. As tape is manually applied to banner material, the resulting hems may not be straight in every instance. For example, if the tape were initially applied at a slight angle, the tape could be significantly off-line towards the opposite end of the banner. This type of error is exacerbated when tape is applied to longer banners such as those measuring four or more feet. To correct an error in alignment, the worker may have to remove the tape or reapply the tape which results in a loss of material, time or both. The formation of hems with double sided tape may also be problematic in that bubbles or other irregularities can be produced when the edge of the banner is folded down onto the tape and adhered thereto. Aside from the problems of alignment and bubbles, current methods of forming hems into banners with the use of double sided tape are both labor and time intensive. Accordingly, there remains room for variation and improvement within the art.